Providing wireless communication services with the exponential growth in wireless data traffic may require substantially denser deployment of base stations or wireless access nodes. The feasibility of a dense deployment of wireless access nodes is predicated on the existence of a backhaul network that can provide high-data-rate transport for each individual access node in the network. Optical-fiber-based backhaul solutions are desirable for maximizing capacity and are well-suited for new construction. For existing buildings and infrastructure, however, installing new optical fiber to every access node in such a dense network can be cost prohibitive.
An alternative is a wireless self-backhaul solution, where the same access spectrum is used to also provide backhaul transport. Using self-backhauling, an access node serves its own assigned user equipments (UEs) in its vicinity and serves its neighboring access nodes as a relaying node to transfer data to or from an information aggregation node in the network. A group of self-backhauling access nodes can form a multi-hop mesh network. Access nodes cooperatively transfer each other's traffic to and from the aggregation node.
Because of the broadcast nature of wireless medium, interference can limit the network throughput for a wireless multihop backhaul network. Interference-aware routing is one solution that offers a significant throughput gain over shortest-path routing. Some interference-aware solutions may include joint routing and resource allocation for wireless self-backhaul networks.
These interference-aware routing algorithms attempt to avoid inter-path interference by assuming that each relay decodes its desired message by treating other signals as noise. This approach, however, incurs significant limitation on network throughput at high load (i.e., the number of sources is large). This result is expected because avoiding all inter-path interference at a high load is nearly impossible. Furthermore, because the transmission rate on every route is determined by the minimum of all link-capacities on the route, one strong interference on a path can drastically degrade the end-to-end performance.
The process in interference-aware routing by which each relay on a route decodes its desired message (by treating other signals as noise), re-encodes it, and then forwards it, may be referred to as decode-and-forward (DF). Other alternatives may use a transmission scheme in which operation at a relay is referred to a quantize-map-forward (QMF) (also referred to as noisy network coding). Using QMF, each relay quantizes its observed signal, re-encodes (or randomly bins) it, and forwards it. Because the relay does not decode the message, the relay is not constrained by decoding (unlike DF). In fact, any interfering signal that the relay receives will be forwarded through QMF and treated as a useful signal at the destination node. For this reason, QMF may perform better than a DF scheme. QMF, however, typically requires high complexity joint decoding, which is hard to implement in practical systems.